About Variables

Hello [mention:4de4ccc7bc0a4873ba4ae1865db3ad49:e9ed411860ed4f2ba0265705b8793d05] 

Variables are used to store values, which can be changed during execution of your code or process. You can define the type of variables and use them for storing the same type of value (Integers, text, Boolean etc.) , using these variables you can transform or change the data in your code or process. 

In Appian we have Local variables, Rule Inputs(Global Variables) and Process variables.

I would recommend you to go through the documentation for better understanding. 
1. Local Variables
2. Interface variables and Inputs

3.  Process Variables

Variables are Containers to store your data. They help you to hold and transport your data from one node to another. 

In Appian We got Rule inputs , Local variables , Activity Class Parameters ,process variables.

Rule inputs and Local variables works in context of Interface.

Local Variables :  Local variables are a specific type of variable that are only available within the context of a particular expression and can only be accessed within the function that defines them.   https://docs.appian.com/suite/help/23.4/Local_Variables.html#overview

Rule Inputs :Just Like Global variables in java.  

Usage:

• pass data down and up interfaces
• pass data into and out of a process model
• pass inputs to expression rules

ACP's and Process variables we use them in context of Process Models.

ACP : These are like Local variables but context is Process Node . Only available within Particular node That we created. https://docs.appian.com/suite/help/23.4/Working_with_Data_in_Process.html#node-inputs--activity-class-parameters

Process Variables : Global variables but in context of Process.  https://docs.appian.com/suite/help/23.4/Working_with_Data_in_Process.html#process-variables

In general - https://launchschool.com/books/ruby/read/variables

On Appian - docs.appian.com/.../Local_Variables.html